PROJECT SUMMARY Kyle Planck is a PhD Student in the pharmacology program at Weill Cornell Medicine in New York City, where he is a member of the Rhee research laboratory. His research interests include developing a deeper understanding of the biochemical processes at work in pathogenic microorganisms and employing this knowledge to formulate clinically relevant treatments for the infections they cause. At Weill Cornell, Kyle carries out this work specifically within the context of tuberculosis (TB), which is the world?s leading cause of death from an infectious disease. This fellowship application details a research plan that incorporates the acquisition of technical skills with mentorship and career guidance in order to prepare him for his career goal of establishing an independent research laboratory at an academic medical center. Kyle has extensive research experience in biology, biochemistry, and pharmacology, and he brings that research foundation to his graduate work and this proposal, which integrates systems level ?omics? analytical approaches with classical microbiological and biochemical techniques. The goal of this project is to characterize the metabolic effects of inhibiting the tryptophan biosynthesis pathway, which is essential to the survival of Mycobacterium tuberculosis (Mtb)?the causative agent of TB?and is being pursued as a source of potential drug targets. The project has two aims: to determine the mechanism of killing elicited by allosteric chemical inhibitors of tryptophan synthase (TrpAB), which our preliminary data suggests to be more complex than simple enzyme product depletion, and to survey whether TrpAB inhibition results in collateral vulnerabilities in other metabolic pathways that may be targetable as well. By carrying out these investigations, Kyle hopes to provide evidence for the mechanism of action of these drug candidates, shed light on the process of tryptophan biosynthesis and its regulation in Mtb, and reveal novel possibilities for combination therapy, which is required for the effective treatment of tuberculosis. This research strategy proposes to answer these questions by incorporating standard microbiological techniques such as growth curves and colony-forming unit enumeration in tandem with cutting-edge technologies such as inducible genetic knockdown strains, RNA sequencing, targeted and untargeted LC/MS-based metabolomics, and CRISPR interference to probe the biology of Mtb in the context of TrpAB inhibition compared to no drug controls. Systems level omics modalities such as metabolomics and transcriptomics will be used to survey the genetic and metabolic networks controlling tryptophan biosynthesis in Mtb, which will then be validated with genetic and biochemical approaches.